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THE LOCUST BORER 

(Cyllene robiniae) 

AND OTHER INSECT ENEMIES OF 
THE BLACK LOCUST 



o 



BY 



H. GARMAlSr 

Entomologist and Botanist of the Kentucky 
Agricultural Experiment Station 



Reprint from the 2nd Biennial Report of the 
State Forester of Kentucky 



1915 




Oass._ii,/l^^4^ 



Mk^-Mz 



3 



THE LOCUST BORER 






EXTRACT FROM SECOND BIENNIAL REPORT 

OF THE STATE FORESTER OF 

KENTUCKY 



915 




QIl|e ^latc 3)uurual Qlontpattg 

Printers to the Commonwealth 

Frankfort, Ky. 



X). of D«? 
EC 28 |9:S 



THE LOCUST BORER 

(Cijllene rohiniae) 

AND OTHER INSECT ENEMIES OF 
THE BLACK LOCUST 

By H. Gaeman, 

Entomologist and Botanist of the Kentucky Agricultural 
Experiment Station. 



The most serious handicap to the successful growing 
of black locust is the attacks of an insect belonging to 
the family commonly known as long-horned wood borers 
and in entomological writings as Cerambycidae, Its 
family contains many troublesome pests, mostly attacking 
trees of different sorts by boring in their trunks. The 
round-headed apple tree borer (Saperda Candida) is a 
similar insect; the elm borer (Saperda tridentata) is an- 
other; the basswood borer (Saperda vestita), still an- 
other. The cane liorer of bhickberry audi the twig girdler, 
together with numerous other species, all represent the 
same family of insects as the one here treated. They 
are among the most difficult of insects to deal with, and 
represent to the forester what the chinch-bug, Hessian fly, 
cutworm and army worm do to the grower of field crops. 
Few of our native trees are entirely exempt from the at- 
tacks of one or another of these borers. But the black 
locust borer is in this State perhaps the most munerous 
beetle of its family. In the fall of the year the adults be- 
come common on certain flowers. None of the other wood 
borers in any situation is quite so numerous, although a 
red and black one is often seen about the flowers of milk- 
weed and is an exception to the rule in the family as to 
its habits, attacking the stems and roots of milkweed 
instead: of those of woody plants. 



The adult locust borer is an active, slender, black 
beetle about 0.60 inch long-, which may be found in Sep- 
tember and October on the flowers of the common golden- 
rods, upon which it feeds. It is black, with a number of 
cross bands of yellow, one of those on the middle of the 
back being W-sliaped. There is only one other beetle 
likely to be mistaken for it and this is the Hickory Borer 
(Cyllene pictus), which does not however frequent golden- 
rod, and comes out as an adult in the spring of the year. 
My figure, together with these statements, will enable 
any one to recognize the locust borer, and a more detailed 
description may be left for another section of this account. 
The beetles themselves do no harm to locust trees, and 
are not often ol)served about the trees unless one looks 
for them during the period of egg laying. The mischief is 
done by their young, legless, white grubs, with brown 
heads and strong jaws, which bore into the trunks of the 
trees. 

Natuee Aisru Extent of the Injury. 

The burrows made by the grubs occur anywhere on 
the trunks of the trees from the ground up to the 
branches, and, contrary to my impression when I began 
to study their habits, extend out on the branches to where 
these are an inch and a half or thereabouts in diameter. 
It thus proves that no part of the tree above ground is 
free from attack except the new growth and the more 
slender branches. Trees may show dozens of the burrows, 
made at different seasons, so that neglected ones finally 
become riddled! with burrows, though those of individual 
grubs remain independent commonly. The direct damage 
is severe enough to render trees worthless for posts, but 
if it were not followed by decay, might not result in the 
destruction of the trees. As a matter of fact, but few 
trees are killed outright, though they lose their branches, 
become knotted and stunted and simply remain breed- 
ing places for the beetles. Many trees kept about premises 
for shade are now in this condition. The locust is a very 
hardy tree, and even with its heart wood largely gone 
as a result of water admitted by the borers, it will stand 
for years, giving rise each season to a score or more of 
the beetles. The seriousness of the damage done becomes 




Fig. 2. A, B, C, and D, eggs of the locust borer, as they 
appear after being thrust by the beetles into crevices in the 
bark (X 2). 



more apparent to the man who tries to raise locusts for 
posts, or who buys posts and wants sound ones. With 
several burrows reaching- in toward the center of a post 
in every foot or two of length, the life of a post is bound 
to be gieatly shortened by decay, and the grower finds 
his profits cut down because of his ina1)ility to furnish 
sound posts. 

There is no part of Kentucky, apparently, in which the 
borers are not present, and their numbers are in propor- 
tion to the abundance of locust trees. In Bluegrass 
Kentucky they are exceedingly common, and this state- 
ment applies to all that territory about Lexington, Paris, 
Covington, Frankfort, Sholbyville, Louisville, and west- 
ward to the Mississippi liiver, with locust in some south- 
ern counties, for some unexplained reason, less injured 
than they are along the Ohio River. Eastward the in- 
jury becomes somewhat less also, and the adult borers 
are less often seen on the goldenrod. I have visited no 
part of the State, however, where the adult beetles were 
not found if the visit was made during the time when they 
are abroad, and my search for them this fall in mountain 
counties, where they are least common, showed them to be 
present in small numbers there. 

Their local scarcity thus appears to be a matter of 
scarcity of the trees, and seems to be the condition that 
prevailed when the locust was only found growing wild 
in the forests. The planting of trees for shade about 
premises pit! along roadsides has doubtless been followed 
by a great increase in their numliers. Any general tend- 
ency to grow trees in a commercial way for posts is thus 
likely to be followed by a still further increase in the 
number of beetles unless we can find a means of lessening 
their numbers. The outlook appears unpromising, but I 
am stating the facts, since these are the only basis upon 
which success in producing locust posts can be l)ased. If 
we cannot get rid of this injury, it is useless to talk of 
grov;ing sound posts for the market. 
IxjUEY TO Locust Plantings Made for the Production 

OF Posts. 
Already a few enterprising men in the State have 
started plantings with the object of producing posts, and 
pai't of these trees have now been examined by us to 



learn if possible the conditions under wliicli injury is most 
severe. The trees will grow almost any^^here, a peculiar- 
ity which gives them an advantage over catalpa and otlier 
forest trees which might otherwise compete witli them for 
favor. The poorest clayey hill will produce locust very 
well, whereas the planting there of catalpa would be a 
waste of time and money. As a matter of fact, black locust 
gathers nitrogen from the air and thus improves poor 
soils where other trees would deplete them. But poor land 
in which some of the Kentucky plantings have been made, 
is also likely to be surrounded by neglected land, and on 
neglected land the rank growths of Solidago (goldenrod) 
in the fall of the year furnish forage for the beetles. The 
injury is thus sometimes severe on such land, not be- 
cause the trees are less well adapted to it, but because 
the other conditions favor the beetles. On good land with 
the surrounding region in close cultivation the beetles are 
at a disadvantage in getting food during the period ivhen 
they are out of the trees. The fact here stated I consider 
one of the important ones learned by a study of the in- 
sect. It will be dwelt on later in discussing the food 
habits of the beetle. 

The Owenton Planting. 

One of the largest plantings known to me is located 
at Owenton in Owen County. The tres grow here natur- 
ally in perhaps as large numbers as anywhere in the State, 
and the conditions for growing trees in a commercial way 
are exceptionally good, excepting for the depredations 
of the beetles. Col. E. C. Ford has at his place perhaps 
a hundred acres planted in locusts. Some of the trees 
are now of a size suitable for fence posts, others are 
smaller, the range in age being from one to six years. 
The land is poor, badly washed and gaillied in places, 
though the plantings have in part been made to stop this 
cutting up of the surface and the accompanying rapid 
washing away of the soil. Col. Ford thinks the trees have 
more than repaid the cost of planting in checking this 
removal of the surface. 

Nearly all of the trees were found badly infested 
July 28-30, when examined by Mr. Jewett, of the Division, 
the older trees having suffered most. Isolated trees and 




Fig. 3. Two eggs, greatly magnified 
(X 18), in crevices of bark. 



clumps growing along roadsides had suffered with the 
rest, and it was evident that the beetles had concentrated 
in the vicinity as the trees became numerous. Some differ- 
encp in fa"^"0T" of trees growing near the bottom of slopes 
was noted, due probably to the better soil, which kept 
the trees m a better condition to withstand attack. 

Some dead trees were noted, the result of drought, 
borers, and poor soil combined, but probably few or none 
were actually killed by the borers, though many of the 
trees showed dead branches which had evidently been 
killed by the insects. Trees which had been cut for posts 
were badly damaged by the burrows. 

Trees from three to five inches in diameter were in 
every case damaged by borers. Those from two to three 
inches in diameter of trunk were less injured, the per- 
centage being about fifty per cent. The youngest trees, 
of a season's growth, showed no injury and were thrifty 
in appearance. The instinct of the beetles seems thus to 
warn them that the seedlings are too small to afford 
sustenance to the larvae. 

The young cut out of the trees at Owenton were well 
advanced in development, and the condition of the bur- 
rows showed that they were approaching the period of 
pupation. The holes always cut by the larvae just pre- 
vious to becoming pupae had in some cases been made, 
from which it appears that the condition was much like 
that at Lexington at this time. 

Other insects were doing little injury to these trees. 
The bag worm (Thyridopteiyx epliemeraefonnis) was 
common. Some leaf hoppers were collected. Leaf miners 
had been working on the leaves, but had at the time left 
their mines. 

The Shelbyville Planting. 

On August 14, 1914, a planting occupying about twen- 
ty-five acres of ground, and another of five acres, were 
examined on the premises of Mr. Frazier. The larger 
planting was twenty-seven years old, the trees ranging 
from five to eight inches in diameter of trunk, while those 
of the younger planting averaged a1)out four inches. 

The land was very badly gullied when planted, but 
at the present time the gullies are largely obliterated 



8 

through the influence of the trees, and has undoubtedly 
been improved by their presence otherwise. The only 
other trees noted in the neighborhood were scattered 
trees along the roads. 

These trees appeared to be in much better condition 
than those examined at Owenton. The foliage was of good 
color and no dead trees were seen, though dead branches 
were sometimes observed on trees by the roadsides. Very 
little evidence of the presence of borers was found and the 
damage done seems not to be very severe. Fence posts 
were cut from the planting in 1913 to the value of $1,200, 
and were only slightly damaged. 

The reason for the inmiunity of these plantings as 
compared with others we have examined was not appar- 
ent and is yet to learn. 

Young of the beetle taken from trees were changing 
to pupae or preparing to do so. The exit holes had iDcen 
cut in the majority of cases, and the plug of shavings 
placed in the burrow above the insect. 

Plantings at Moeganfield, Union County, 
October, 2, 1914. 

Mr. G. L. Drury at Morganfield has a planting oc- 
cupying several acres which, with numerous trees grow- 
ing in the vicinity, was examined October 2, 1914, by Mr. 
Niswonger. The region, like that at Owenton, seems ex- 
ceptionally suited to black locust, and trees were found 
everywhere along" roadsides, fence rows, creeks, etc. A: 
small planting examined at this place appeared to have 
been completely killed by the insect, with the exception 
of the larger trees. On Mr. Drury 's place the trees, aver- 
aging about three inches in diameter of trunk, were 
severely injured, some of them killed. 

At Waverly, Kentucky, a planting of about seven 
acres was examined on the place of Mr. H. A. Roberts. 
The trees w^ere planted in 1887 and ranged from six to 
eleven inches in diameter of trunk. The larger trees 
seemed to be little injured, but the yomig ones showed 
the exit holes made by beetles. Dead trees, of which a few 
were observed in this planting, a])peared to have been 
injured by other agencies than the beetles. This planting 
had been grazed by sheep. 



9 

The adult beetles were found to be common on golden- 
rod in the locality, sometimes at a distance from trees, in 
one instance a half inile from the nearest observed tree. 
All about the small two-acre planting on Mr. C. F. More- 
head's place, noted above as veiy badly injured, golden- 
rod grew in ^^I'ofusion and some plants were scattered 
among the trees. In fields and along roadsides also golden- 
rod was excessively common, and everj^where harbored 
large numbers of beetles. On the trees the beetles were 
ovipositing, and eggs were found hatching, while others 
had already given up the young. This was at eleven 
o'clock in the forenoon. About Mr. Drury's place, also, 
the goldenrod grew eveiy^vhere in adjacent fields and 
along roadsides. At 2:30 p. m. the beetles were noted 
running up and down the trees looking for places to con- 
ceal their eggs. At the same time large numbers were 
about the flowers, many of them mated. 

On Mr. H. A. Roberts' place at Waverly the injury 
appeared to be less than in other plantings, a condition 
explained jDerhaps by the fact that his land w^as kept 
clear of weedy growths and the locust planting itself 
had been grazed by sheep. Few beetles were observed 
here, and very few goldenrod plants, a condition the re- 
verse of the others examined about Morganfield. 

Small trees planted at one edge of his farm had, 
however, been badly injured and in their vicinity golden 
rod was common. Both trees and flowers bore numerous 
beetles at the time of Mr. Niswonger's visit. 

St, Beknaed Coal Company Plantings, at Central City, 
October 3 and 4, 1914. 

At Central City several plantings, from a few acres 
to sixty in extent, were found to agree in general with 
those already mentioned. The beetles had done most mis- 
chief where goldenrod was most numerous and the 
injury diminished even on parts of one planting as the 
goldenrod became less common, A section near the rail- 
road w^here goldenrod continues from year to year had 
been largely killed by the beetles and hundreds were ob- 
served on the flowers, twenty-five beetles being counted 
on one small clump of plants. The adults were observed 



10 

to be mating at eleven o'clock in the morning; eggs just 
hatching, others that had hatched were found, sometimes 
on dead trees. 

A forty-acre planting at this place was found to cor- 
respond with those inspected elsewhere, in that where the 
open spaces occurred in which goldenrod was established 
the injury was alwaj^s worst and in isolated sections 
where there was no goldenrod the trees Avere nearly 
perfect. 

A La Grange Planting. 

October 6, 1914, a planting of two thousand black 
locusts at LaGrange was examined. It had been killed 
by fires. The trees were planted in 1903 and in some 
cases had a trunk diameter of four inches, though mostly 
less. The planting was badly infested with goldenrod, 
about half done blooming, upon which were found some 
beetles. A few mating beetles were noted (3-5 P. M.), and 
females were observed looking for places to deposit their 
eggs, on partly dead trees. The dead trees observed 
showed numerous marks of infestation. 

Summary of Examinations Made in 1914. 

While the beetles fly like bees when disturbed and 
travel some distance to find food, it is evident from the 
work thus far done that there is a relation between the 
abundance of goldenrod and the prevalence of injury. 
Wherever a planting adjoins land on which goldenrod 
is exceptionally common the injury is severe. Wherever 
the planting is awa}^ from growths of goldenrod the 
injury is proportionately less. The insects certainly do 
most harm where the food plant upon which the beetle 
depends is most numerous, and this suggests the possi- 
bility of controlling the injury to a great extent by de- 
stroying this plant whenever it is seen in the vicinity of 
locust trees. 

The Food Plants of the Adult Borer. 

The important relation sustained by the goldenrods 
to locust injury in Kentucky led me to observe these 
plants more closely in 1915, with a view to learning what 



11 

species Avas most resorted to by the beetles. From the 
examinations made in 1914 it began to appear that one 
species of plant (Solidago altissima) furnished most, or 
all of the food taken by the adult beetles while their eggs 
were maturing. This has proved true in great measure 
as a result of observations made in 1915. The period 
during which the insects are out of the trees corresponds 
with remarkable closeness with the period of blooming of 
this common species. The beetles may be said to depend 
upon it for food. But, contraiy to my first impression, 
they are not restricted to it. We have a species (S. can- 
adensis) bearing a close resemblance to S. altissima, but 
with smaller heads of flowers and an earlier period of 
blooming, upon which the beetles first to emerge were 
found. But they were few in number, and the plant evi- 
dently is not an important forage for the insects, except- 
ing as it may tide over the early maturing beetles until 
the more acceptable j^lant is in bloom. Still another 
species besides S. canadensis was observed to have at- 
tracted a beetle at Corbin, Kentucky, this fall, and a cul- 
tivated species with broad leaves (8. rigida?) obtained 
from the Henrj^ Dreer Seed Company of Philadelphia, 
and kept during the past season at the Conservatory of 
the Division, attracted a few beetles. So it is evident 
that they get some food from other species of goldenrod 
at times, and would probably resort to any of the species 
in the absence of their favorite. I had supposed they 
were restricted for food to the genus Solidago, but this 
also seems not to be true. On one occasion at Lexington, 
Mr. Jewett, of the Division, found a beetle on a native 
plant with white heads of flowers (Eupatorium sero- 
tinum). It grows in Avet ground about ponds and is one 
of the Joe-Pye weeds and a member of the same botani- 
cal family (Compositae) as the goldenrods. I have my- 
self several times taken the beetles during the season 
of 1915 from another species of the genus (EupatorUim 
perfoliatum) knoAvn as Thorowort or Boneset. It also 
has Avhite flowers. These plants are, however, not as 
generally scattered about fields as are the goldenrods 
and are thus of much less importance as food for the 
beetles. Their time of blooming comes very close to the 
period of emergence of the beetles. 



12 

I have had it reported to me that the beetles visit the 
flowers of the Marigold, an old-fashioned flower of onr 
gardens. The statement seemed so contrary to what we 
know of the insect that I wished to verify the observa- 
tion and see to what extent this exotic attracted these 
native insects. With this in view I had jjlanted a nmn- 
ber of varieties, both African and French, dwarf and 
tall, in a plot of gronnd near the Conservatory. They 
made a fine growth and prodnced a great wealth of flow- 
ers. Several species of Solidago were planted near them 
and a short distance away were some young locust trees 
to which some beetles were attracted. Adult beetles were 
present on the goldenrods Ihroughout most of the period 
when the insects were abroad. I examined the marigolds 
repeatedly and did not find a single beetle on the flowers. 
Such beetles as visit these plants must, I think, be 
strays that have alighted during their wanderings in 
search of locust trees or of goldenrod. 

In brief, the important food plant of the adult locust 
borer is one species of goldenrod, the Solidaijo alfissinia, 
already mentioned. Wandering beetles may alight on 
the flowers of other plants at times, but with the excep- 
tions noted above this appears to be only temporarily. 
Asters and other flowers which were common in the im- 
mediate neighborhood of goldenrod this season were 
visited by large numbers of other insects, but in not a 
single case was a locust borer noted about them. On the 
other hand, any isolated clump of Solidafjo altisslma was 
likely wdien in full bloom to be visited. A small clump in 
my yard was generally frequented by several of the bee- 
tles, day and night, during September. 

The Food and Feeding of the xVdult Beetle. 

The activity of the beetles about the flowers of gold- 
enrod at once arouses one's curiosity as to what they get 
from the flowers, and why it should be necessary for them 
to feed so constantly after they emerge from the trees. 
They are as industrious as bees and almost as active, 
eating away steadily, but dropping to the ground, or 
taking wing quickly, when approached. An examination 
of the contents of the alimentary canal throws light on 
this subject: The part of the flower eaten is the pollen, 




Fig. 4. A number of eggs deposited under the bar 
old excavation (X 3). 



in au 



13 

and they are thus rivals of the bees in collecting this nu- 
tritious food. The beetles mature but slowly after they 
cast the puj^al skin in their burrows, and remain for a 
long period without food, the body white and soft, the 
colors gradually appearing and the crust becoming 
harder, until about the time the goldenrod begins to 
bloom, the first ones come out, the numbers rapidly 
increasing until in late September when they may be 
found wherever there are locust trees and goldenrod. 
AVithout the two, one to provide food for the larva, the 
other for the adult, this insect would probably not long 
continue abundant. 

It seems to me, therefore, that the general destruc- 
tion of goldenrod in the vicinity of locust plantings w^ill 
lessen the in.iuries of the beetles, if it does not entirely 
prevent it. For it is evident that this plant furnishes 
the stimulating food necessary for the development of 
the eggs of t]ie female ; and as a matter of fact I find that 
beetles confined without food of this character soon die, 
while those provided with it live and place eggs on the 
bark of sections of locust trees furnished them. 



LiFE-HISTOEY OF THE LoCUST BOKER. 

After mating, the beetles begin to resort to the 
locust trees for the placing of their eggs. Eggs may be 
found on the bark of trees about the middle of September, 
In 1914, they were found in some numbers September 
17. The females run up and down the trunks and larger 
branches, searching for suitable crevices in which to 
liido the eggs, generally placing them well under loose 
bark, but often leaving one end, or in some cases' the 
larger part of the length exposed. They are scattered 
about indiscriminately anywhere on the trunk and 
larger branches, and may be found on some of the latter 
which are only an inch and a half in diameter. The 
greater smoothness of the bark on small branches 
seems to deter the placing of eggs to some extent, and the 
majority are ordinarily found on the trunk where they 
can be better concealed. Sometimes a half dozen or 
more eggs may be placed close together, as shown in one 
of my figures. By September 22, egg-laying is most 



14 

active, and in the middle of the day numerous beetles can 
be seen running about the trees engaged in this task. 

Eggs were observed hatching on September 25, but 
the beetles were still numerous on goldenrod and con- 
tinued so until the middle of October, and eggs were ob- 
served hatching as late as October 1. Many eggs are 
placed on trees subsequent to this date, however. On 
October 4, 1914, near Versailles in Woodford County, I 
found beetles still common on goldenrod, and from 11 
A. M. until 1 :30 P. M., observed them placing their eggs 
on the trunks of locust trees. 

They were observed again October 22, 1915, near 
Frankfort, on goldenrod, but were less common at this 
date than in 1914, because of a couple of early frosts 
which had destroyed most of the goldenrod. 

As soon as hatched the young grub bores into the 
outer bark, throwing out refuse as it burrows, so that 
the point of entrance can generally be detected. It does 
not go very deep in the fall of the year, simply penetrat- 
ing the outer bark and making a small oval cavity next 
the wood where it ceases boring and lies torpid during 
the winter months. Some of the burrows at this stage 
are represented in one of my figures. 

With reference to the condition in which the young 
borer passes the winter, the following entries in my notes 
on the life-history may be quoted : 

Nov. 17, 1914. Our first really cold weather began 
last night. The adults and Solidago disappeared some 
time ago. A piece of young tree about 3i/. inches in di- 
ameter examined today. The eggs on the bark were 
marked earlier in the fall. Young are few in number and 
have not penetrated as deeply as was expected. Three 
w^ere discovered just beneath the outer corky layer of 
bark, the cavities in which they lay being scarcely larger 
than the bodies of their respective grubs. One cavity 
measures 4.3 millimeters (0.132 inch) in length and 2'""^ 
(0.08 inch) in diameter. The grub measures 2.6™'^ or 
about 0.10 inch in length. These little chambers are 
marked by a yellow stain outside each, due to the pres- 
ence of the grub, probably to some secretion it produces, 
and which softens the wood, preparing it for more rapid 
appropriation by the weak mandibles and probably ren- 




Fig. 5. Eggs, greatly magnified (X IS). 



15 

dering it more digestible. This yellowed wood extends 
about 3.4"^"^ outward in all directions from the cavity. 
The little grub lies not more than S""*" (0.12 inch) from 
the outer surface of the bark. 

Grubs torpid; move scarcely at all when the burrow 
is opened. 

December 21, 1914. Numerous burrows were un- 
covered today in a section of a tree brought in from out- 
of-doors. All the grubs had stopped just under the 
rough bark and had only made cavities sufficient to ac- 
commodate their bodies. It is evident that they do not 
feed much as grubs in the fall. 

When the GtRubs Become Active in the Spring. 

The real work of mining the tree and feeding begins^ 
with the grub, in early spring, as soon as the trees them- 
selves become active and the temperature rises. On 
April 29, 1915, larvae taken from the trees were found 
to have made but little headway since the preceding fall. 
They were becoming active, however, and an example in 
a branch about three-fourths inch in diameter had pene- 
trated to an old burrow where it had grown much more 
rapidly than the rest. The great majority uncovered at 
this date were not much larger than they were in the 
fall. The stained region about the burrows has by this 
time extended somewhat and the discoloration is of a 
deeper brown color, so that burrows are quickly visible 
on stripping off the outer bark. A typical example 
measured to the outer limits of the stained region 20"^™ 
(0.80 inch) by 8"^'^ (0.32 inch). These stained regions 
were elliptical or oval in shape, the stained wood begin- 
ning to break away at the edges from the living wood 
outside. The region has a peculiar sour odor at this 
time, due to some fermentative action set up either by 
the secretions of the grub or by bacterial organisms 
introduced by it from outside. As already stated the 
stain appears as soon as the recently hatched grubs 
reach the inner bark, and extends on all sides as the 
insect grows. 

By June 15 the grubs have made shallow burrows 
l)eneatli the corky layer of bark measuring from about 
O.GO to 0.80 inch in diameter, with a depth of about 0.20 



16 

inch. Then at the upper end of this cavity it bores up- 
ward and inward toward the center of the trunk, in small 
trees reaching the center, then descending in the heart 
wood for a distance of about three inches. As refuse 
accumulates in the inner descending limb of the burrow 
it is pushed upward and over the bend to fall into the 
outer chamber made by the young larva. Ordinarily 
the grubs do not leave the descending limb of the burrow 
after it is made. The inner burrow is nearly uniform in 
diameter but may increase a little toward the lower end, 
Avhere it measures in an example before me 0.40 inch. In 
large branches and in the trunks of trees the burrows do 
not reach the center, and in most of those examined the 
descending part runs downward parallel with the surface 
and just about an inch from the surface of the wood. 

When sections of this wood were brought indoors 
from June 15 to June 20 the larvae continued active in 
them for some time, and as they lay on my table the 
slight noise made by their gnawing operations could be 
heard constantly, while a small heap of particles grad- 
ually accumulated on the table beneath each burrow. 
The drying out of these sections had the effect of hur- 
rying the transformation of the grubs, however, and on 
June 29 in one instance a piece of branch about 18 inches 
long in which were several larvae, ceased to give forth 
refuse, and it became evident that the grubs were either 
dead or had begun to pupate. On cutting into the bur- 
rows July 11, it was found that in one Avas a pupa 
but it was dead. It was about 0.72 inch from the 
bottom of its burrow, and was protected from marauders 
from outside by a plug of loose chips made by the grub 
previously, and by another of dust-like particles filling 
the bend a half inch above. The whole burrow in tJiis 
case was small, measuring 2.16 inches deep and 0.14 inch 
in diameter. In exposing this burrow I cut into the 
lower end of another above it, at one side of the first and 
not exactly in the center of the branch. The lower one 
followed the center. This upper burrow contained a 
larva preparing to pupate. Its burrow was closed above 
with chips and dust, but it had not yet molted. A plate 
glass was sealed over this second burrow so that it might 




Fig. 



Locust borers; natural size 
and enlarged. 




g\~l ■!* 






Fig. 8. 



The pujiae of the locust borer; natural size 
and enlarged. 



17 

be observed. It pupated in the iiiglit of July 2, and was 
found in this condition July 3. . 

A singular feature of the habits was observed at this 
time and has since proved to be constant for the insect. 
These grubs, it is to be remembered, have never been 
outside the tree since they hatched from the egg. They 
are not supposed to know anything of adult locust borers, 
having never seen or in any other Avay received know- 
ledge of this stage of their development, yet each borer 
cuts through the wood at the highest point in the burrow 
straight to the outside, so that the future beetle into 
which it will later develop can easily get out of the tree, 
and without having to descend, even if the burrow were 
large enough for the purpose, into the small chamber 
made by the young grub during the fall and early spring. 
Here, as in man}^ other insects, is an illustration of some- 
thing like prevision, foresight, call it what you will ; and 
it becomes the more remarkable Avhen you refuse to 
ascribe to these animals a mind and capacity to think. 
What is it that tells these grubs that the adult beetle will 
be unable to escape from the burrow unless the way is 
prepared for it by the strong jaws of the grub? 

On July 23, 1914, the insect over which the plate of 
glass was sealed, was found to have become adult, but 
its body was still soft and it was below the plug of chips. 
On July 25 it was still below the plug, but when ex- 
amined August 2, had pulled the plug into the bottom 
of its burrow and was in the upper part. It was out 
August 5, and was a small individual, having evidently 
been dwarfed by the drying of the wood, and its develop- 
ment accelerated. 

On August 1, 1914, larvae out-of-doors had begun 
to make plugs in their burrows preparatory to entering 
upon the quiescent pupa stage. On August 10 both 
larvae and pupae were found in the burrows of living 
trees, on cutting into them, but the pupae were not 
numerous, and it was evident from their numbers that 
this is the time when pupation normally takes place. 

Adults were not observed in the trees until Septem- 
ber 2, when examples were found in the burrows, still 
soft and pallid. They were not observed out of the bur- 



18 

rows and on Solidago until September 12, when both 
males and females were observed on the flowers. 

This completes the round for a season ; the egg-laying 
having already been mentioned as beginning about the 
middle of September, and continuing until cold weather 
approaches. 

The Appearance or Infested Trees. 

Old trees about the streets of cities are sometimes so 
badly riddled by the borers that the trunk becomes un- 
synnnetrical and rough wliile many of the branches are 
reduced to stubs and the rest greatly reduced in size, so 
that the crown is small and out of proportion to the diam- 
eter of the trunk. When cut into, such trees are found 
to bear the marks of boring by generation after genera- 
tion of beetles, beginning at the center where they w^ere 
injured when young, and extending out to the bark. 
Quite often the center and large cavities elsewhere are 
eaten out by decay also, yet such trees persist, wrecks 
as they are, year after year, silent testimony to the won- 
derful vitality of the species and the surprising dura- 
bility of its wood. In most of the more closely yjeopled 
sections of the State wherever locusts have been planted 
in any number this is the condition in which many of the 
trees exist. Examination of shade trees about Lexing- 
ton shows that from 50 to 100 per cent, is infested, most 
of them badly so. A tree about six inches through at the 
base and about twenty-five years old (the center was de- 
cayed a. little so as to prevent an exact determination of 
the age), growing on the Experiment Farm, was stripped 
of its bark, June 15-20, from the ground up to the 
branches and then out on the branches as far as injury 
could be detected. It w^as found to be injured by the 
borers from the ground to and upon the branches until 
the latter became less than about 1.33 inches in diameter, 
after which the burrows were no longer present. The 
injury was greater at the bases of the branches than on 
the trunk of the tree, and this accounted for the numer- 
ous dead branches, while the body still retained enough 
vitality to produce foliage on the small branches. 

The position of burrows was always apparent at 
this time because of the refuse consistino- of bits of wood 




Fig. 9. A section of a 
badly injured young locust 
tree. 




Fig. 10. Strips of locust bark removed to show cavities made by 
young borers; A, cavity as it appears in the fall; the rest as they 
appear in the spring (April). 



19 

and tlie like thrown from their entrances as well as by the 
sap which exudes at this season of the year. The aper- 
tures were always small, however, and quite often the bits 
seemed to have been thrown out by a small ant which 
takes up its domicile in the deserted burrows and was 
frequently observed in the shallow excavation made by 
the young borers just under the bark. Single burrows 
cause no serious injury to a tree. Trees with only a few 
would undoubtedly recover and present finally no out- 
ward signs of injury. It is the continued work of the 
insects year after year that finally shows its injurious 
effect, leaving the wood honeycombed with burrows and 
eaten away with the decay that follows them. 

' Descriptions of the Locust Boeer. 

Egg. — Elongate, cylindrical, rounded or slightly 
truncate at one end, more pointed at the other. Smooth, 
opaque, white. Length, .092 inch; diameter, .032 inch. 

Larva. — Cylindrical in general shape, widest just be- 
hind the head, the divisions well marked, about six of 
them protuberant at the sides. Head medium in size, 
brown about the bases of the appendages, elsewhere 
largely wdiite, but with dark sutures beneath and a me- 
dian dot above at the hind margin. When ready to 
pupate, the head may be largely brown. Division of 
body following the head widest, the second and third 
small, the size gradually increasing backwards to the 
tenth, then suddenly diminishing, the last being smallest 
and only about half the diameter of the one preceding- 
it. Nine brown spiracles along each side, the front larg- 
est and out of line with the rest. Ever^^vhere with fine, 
bro^vn, microscopic pubescence, except on certain prom- 
inences along the back and on the under side, which are 
smooth. Four obscure pale brown spots are more or 
less visible above on the division immediately behind the 
head. No legs. General color white. Length of a fresh 
example about ready to pupate, 1 inch; greatest diame- 
ter .26 inch. A larva recently hatched measured .09 inch 
in length and .04 inch in greatest diameter. In general 
shape they are much like older larvae. They are quite 
helpless when removed from the burrow. 



20 

Pupa. — Oval in general shape, the legs, wings, anten- 
nae and other parts of the adult being outlined, but 
folded against the body. On the back of the thorax and 
abdomen are small brown prickles, these being larger and. 
more conspicuous behind. Color white, or yellowish, a 
faint line along the middle of the back. Length .97 inch. 

Imago (Adult). — The beetle is a slender cylindrical 
insect with moderately long legs and antennae. Length 
from about .50 to .80 inch, the males averaging smallest. 
Black, with cross bands of bright yellow, of which the 
third on the wing covers is W-shaped. 

The only other beetle likely to be mistaken for it is 
the hickory borer (Cyllene pictus), which is marked with 
yellow bands in the same pattern, but has longer legs, 
the reddish thighs, reaching to the tips of the wing covers, 
and the second division of the hind tarsi being smooth 
beneath, whereas the same division of the feet of the 
locust borer is pubescent. The adult hickory borer is 
found only in the spring, when it is attracted to the bleed- 
ing stumps of trees that have recently been cut down. 

EXEMIES OF THE LoCUST BORER. 

A common insect like this, living as an adult exposed 
in the bright sunlight, would naturally be expected to 
serve as food for birds and predatory insects. The num- 
ber of enemies thus far observed by us is small. The 
adult beetles are pretty well concealed when on the flow- 
ers of goldenrod by their yellow and black colors, which 
harmonize with those of the flowers much better than 
would be expected from an examination of the insect 
alone. I have not observed birds molesting them at any 
time. A disagreeable odor which they emit when handled 
may be an additional protection. The hard bodies of the 
beetles probably saves them from the attacks of most pre- 
datory insects. The larvae and pupae living within the 
burrows are completely sheltered from most enemies. I 
suspect that the wood is too hard for the beaks of wood- 
l^eckers, the only birds at all calculated to reach them. 

A single large puncturing insect, the wheel bug 
(Prionidus cristatus) has proved a verv effective check 
on the adult beetles, and Vvdiere it is sufficiently common 
destroys them in large numbers. This insect is one of 




Fig. 11. Tlie outiT exciuatioiis made bv borers under the bark 
before they penetrate the trunk. They bore into the tree at the 
upper edge of these shallow outer cavities; natural size. 




Fig. 12. A, A, two excavations of borers tliat are 
ready to pupate, the holes for tlie exit of the beetles being 
cut at B, B; natural size. 



21 

the most formidable of its kind. It is a member of the 
order Hemiptera, a group coiitaiiiing such pests as the 
notorious chinch-bug', the squash bug, the bed bug and the 
kissing bug. It reaches a length of 1.28 inch, is provided 
with a stout beak, and gets its common name wheel bug 
from a toothed and arched crest on the back just behind 
the head. Individuals have been observed on the flowers 
of goldenrod destroying the locust borer adults, and also 
on the tninks of locust trees, where thej^ may be observed 
with the beetles impaled on their beaks. On one occasion 
near McKee in AVoodford County, I found an example 
with a beetle still struggling on its beak. AVitli the wound 
it inflicts the bug injects a clear fluid that probably has a 
paralyzing effect. On one occasion an example taken 
from a goldenrod, managed while I was occupied mo- 
mentarily with something else, to prod my finger, causing 
a sharp pain and subsequent intiannnation and swelling, 
the results being somewhat like that of a bee sting. 

The females when captured sometimes emit at the 
hind end of the body a forked, orange-colored, glandular 
bod}^ with a pungent scent like that of the gland of a cel- 
ery butterfly. It is probably protective. The bottle- 
shaped eggs of this bug are placed in clumps on the 
twigs, and remain in this condition over winter. They 
are laid in September. 

These wheel bugs are doing a great deal of good in 
some localities, and should be recognized and protected 
where this is practicable by those interested in the grow- 
ing of locusts. 

Adult locust borers dying in confinement are some- 
times parth^ covered by a white fungus which emerges 
at the articulations between the divisions of the body. 
It may prove to be one of the parasitic fungi such as 
destroy the chii^-ch-bug and other insects, but has not been 
studied carefully. From the free life led by the adults 
they are not so much exposed to the attacks of such fungi 
as are insects living concealed in moist situations. 

Other Ixsects Ixfestixg the Wood of Locust Trees. 

Several other insects are found in the burrows of the 
locust borer, some of them appearing to be pretty con- 
stant guests in the outer parts of burrows and especially 



22 

in the old cavities. The small ant has already been 
mentioned. The larva of a small beetle is also frequently 
seen, and seems to be the young of a sap-lover, and one 
of the Nitidulidae. The egg-cases of roaches are some- 
times found in the refuse of old cavities comnmnicating 
freely with the exterior. A small gray beetle of the 
same family as the locust borer (Cerambycidae) has 
been occasionally found in the old burrows, and some- 
times on the bark of the trunk. 

Some examples of the Carpenter Moth (Prionoxys- 
tus robiniae) have been encountered by me in opening 
up the burrows of the locust borer. One of them brought 
in July 6, measured two inches in length, with a diame- 
ter of 0.44 inch. These big worms are more formidable 
in appearance than the grubs of the borers. They are 
yellowish white, with a series of poorly defined brown 
spots along each side of the back, and another lower 
down on each side. The head is deep chestnut brown, 
becoming blackish about the mouth. It can quickly be 
distinguished from the borer by the presence of three 
pairs of jointed legs just behind the head, no trace of 
such appendages being visible on the locust borer grub. 
The adult of the carpenter worm is a moth, and it thus 
belongs to an entirely different insect order (Lepidop- 
tera) . 

It would be possible to give a long list of insects 
that attack the wood, living or dead, but it would only 
cumber this paper and serve no useful purpose. There 
are, however, several species in Kentucky besides the 
Locust Borer (Cyllene robiniae) and the Carpenter 
Moth (Prionoxystus robiniae) already mentioned, that 
do some mischief at times and are of interest to the 
grower of young trees. 

The Twig Miner (Ecdytoloplia insiticiana). Per- 
haps the most important enemy of nursery trees is 
a small moth whose young bores into and mines the 
twigs of young trees. It has been found this year on a 
planting made by the State Forester at Louisville, and 
is constantly injurious to young trees about Lexington. 
The injury may commonly be recognized by an elongate 
swelling of the twig, with an opening at the lower end, 
between two thorns, from which protrudes a mass of 




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Fig. 14. Back and side views of the 
wheel bug. male (upper), and female 
(lower) ; natural size. 



•23 

refuse which has been thrown from the burrow by its 
occupant. Some of the mines show no swelling of the 
twigj but in such cases their location can be recognized 
by the mass of refuse. The interior of such twigs is 
mined lengthwise by a small yellow, or, finally, bright 
crimson larva, with a reddish brown head and a black- 
ish brown neck-plate just behind it. It moves quickly, 
and when ready for the next change comes out of the 
mined twig and roams about looking for a place to 
form a cocoon in which to lie during the pupa stage. In 
confinement most of them made odd little oval cases by 
cutting out pieces of two leaves lying in contact, fasten- 
ing them together with silk ^nd undergoing the change 
within. They lie for a long time in these cases as larvae, 
however, assuming finally the bright crimson color men- 
tioned above. Most of them failed to emerge, but in two 
cases adult moths appeared, one from the cocoons, the 
other from sand and rubbish in the bottom of the rear- 
ing jar. Some of the larvae which made cases for pupa- 
tion in the latter part of AugTist were still unchanged 
September 4. One of the adults secured came out Sep- 
tember 8, leaving the pupa skin protruding from the 
case. 

Several broods appear to develop during a season. 
At any rate, after the brood secured in August as larvae 
had all emerged for pupation, and I supposed the winter 
would be spent in the adult or egg stage, young larvae 
were again found in the trees. In October, near Dun- 
can, in Franklin County, these young larvae were quite 
common. We have not yet had an opportunity to leam 
just where and in what condition this late brood passes 
the winter. 

Treatment for this pest consists simply in cutting 
out and burning the infested twigs. They can be so 
readily seen that this procedure involves no great dif- 
ficulty. Spraying early in the season with arsenate of 
lead may be suggested also, since it is as reasonable to 
suppose that this treatment will be as effective as it is 
for the codling moth of apple. It remains to be tested, 
however. 

Agnhis e genus. — A second insect that attacks the 
wood is to be mentioned here because of its constant 



24 

presence and occasional abundance in locust trees. It 
is a small, slender-bodied, bronzy beetle of the same fam- 
ily as the flat-headed apple tree borer, and like the latter 
works under the bark. Its injury as a bark beetle is not 
often apparent, but the adults are common on the leaves, 
and have a very singrilar way of chewing the edges of the 
leaflets so as to give them a rough appearance. The 
roughness is so slight, however, as easily to be over- 
looked. The mischief is not of great importance, except 
when taken with that of numerous other leaf-gnawing in- 
sects of locust trees. It could doubtless be controlled by 
the use of a spray of arsenate of lead. 

Insects Attacking the Young Twigs and Leaves. 

The leaves of black locust harbor at all times a large 
number of insects representing a long list of species. 
They attack the leaves in various ways, some by gnawing, 
some by puncturing, some by mining them, etc. 

Leaf Miner No. 1. — The Black and Yellow Locust 
Hispa (Chalepus dorsalis). — Among the leaf insects in- 
festing the trees this is the worst. The adult is a small 
yellow and black, flattish beetle often found among the 
leaves, and sometimes in this condition doing a good deal 
of harm. Its eggs are laid in packets, each of about five 
flattened, somewhat triangular eggs. On hatching the 
young all bore into the leaf and make a mine between the 
two cuticles, upper and under, their food consisting of the 
green substance of the leaf. By gnawing this away the 
foliage is soon made to assume a brown hue, and as the 
little miners scatter and make new mines for themselves 
the whole foliage of a tree may be embrow^ned by the 
latter part of the summer, giving it the appearance of 
having been damaged by fire. The little grub in each 
mine ceases feeding after a while, becomes a quiescent 
pupa lying in the middle of the mine it has made, and fin- 
ally emerges as a beetle to mate and lay eggs for a new 
brood. One brood becomes mature in July, and another, 
generally less numerous, matures in late summer and 
passes the winter among rubbish under the trees. 

A second smaller brown beetle of the same genus 
(Chalepus nervosa) is common as an adult about locust 



Fig. 15. Two views of a twig occupied by a twig miner, showing 
also the bug, Thelia bimaculata, and its striking resemblance to one 
of the thorns; natural size. 




Fig. IG. The cases made by the locust twig miner 
by cutting out ovals from two leaves, when ready to 
pupate. The figure at the right, of natural size. 



25 

trees and feeds upon the leaves, but its early stages have 
not been secured by me from this tree. 

In addition to these beetle leaf-miners the locust 
trees in Kentucky are infested by a small group of moths 
Avhich in their larval stages mine, or skeletonize, the 
leaves. They were more connnon during the season of 
1915 than the Locust Hispa. The following paragraphs 
are taken from an article of mine published a good many 
years ago, and not now accessible. They will give an 
idea of the nature of the injury and the character of the 
insects : 

Leaf Miner No. 2 (Gracillaria lespedezifoliella). — 
Several other insects make blisters on the leaflets not 
verj^ different in general from blisters made by the young 
Hispa. The casual observer is likely to mistake the lat- 
ter for the ones already described. One of these is pro- 
duced by the larva or grub of a moth, about the size of 
the common clothes moth so troublesome in dwellings. 
It is in fact a closely related insect. The blister when 
fully formed may be recognized by the fact that it lies 
along the midrib of the leaflet, and has processes or 
lobes extending out toward the margins. It is yellowish 
brown in color and is narrowly edged with reddish 
brown. To distinguish it from other blisters, I have 
named it in my notes the digitate blister. The grub is 
somewhat flattened like that of the Locust Hispa, but is 
more slender. The manner in which these blisters are 
formed is so curious that I must describe it for the bene- 
fit of those interested in insect architecture. xVbout June 
1, small wiiitish triangular blisters occur in- the angles 
formed by the junction of the veins and midrib on the 
under side of leaflets. No one would suppose they had 
anything to do with the digitate mines of the upper sur- 
face, which appear somewhat later. But they are the be- 
ginnings of digitate mines. The little moth places a sin- 
gle lens-like Q^g at the edge of a vein about one-eighth 
inch from where it joins tlie midrib. The grub, hatcliing 
from the Qgix,, bores into the leaf at once, and then makes 
a narrow mine along the vein until the midrib is reached, 
when it mines along the latter in the same way and for 
about the same distance, the mine being now V-shaped. 
Then it turns back on its course and mines alongside the 



26 

second arm of the V until the angle is reached again, 
when it goes out along the first-made arm, onh^ to return 
when it reaches its extremity. And thus it continues un- 
til all the space included between the arms of the V is 
mined, and the little blister is triangular in shape. In- 
stead of continuing on the under side of the leaf the grub 
now cuts through to the upper side of the midrib and 
makes a larger mine along it, at first linear in general 
shape, but gradually extended until finally it assumes the 
digitate character of the completed blister. While the 
grub is yet small it will, when its mine is laid open, re- 
treat promptly into the triangular mine of the under side. 
At least two broods of this insect develop each season, 
the second lot of mines appearing in the latter part of 
August. The moths are so retiring in habit that they 
are not often seen. Just how it passes the winter I am 
unable to say positively, but it appears to leave the blis- 
ter, and it is probable that it becomes a pupa among 
leaves on the ground beneath the trees. The adult moth 
is brown, the fore-wings marked with three oblique sil- 
very lines shaded with dark brown, and with as many 
silvery dots on the inner margin. 

Leaf Miner No. 3 — Ostensacken's Leaf -miner (LitJi- 
ocoUetes ostensackeneUa) . — A third very common blister 
on locust leaves is produced b}^ the larva of another small 
moth, also much like the clothes moth in structure. It is 
one of the most beautiful midgets when it has acquired 
wings in the whole range of animated existence. The 
fore wings are of a rich brown color and shine as if made 
of burnished metal. Each wing is crossed by four sil- 
very lines, edged in front with black, the two outermost 
broken at the middle. It is not more than an eighth of an 
inch long from the front of the head to the tips of the 
folded wings. This little moth places its flattened eg^x; 
either on the upper or under surface of the leaflet, and 
is also indiscriminate as to the part of the leaf chosen. 
The recently hatched grub makes at first a tortuous mine, 
but soon abandons this style of construction and enlarges 
it into a more or less round blotch-mine of a yellowish 
brown color. The worms change to pupae in silken cases 
which they spin within the mines. 




Fig. li. The adult Locust Hispa (Chalepus 
dorsalis), greatly magnified (X 12). 




Fig. 18. The Digitate leaf mine; natural size. 




Fig. 19. A, the Digitate mine when first 
made on the upper side of a leaflet; B, the 
mine when completed; C and D, mines as 
first made in the angles of veins on the under 
sides of leaflets, in various stages, the two 
upper ones at the left being nearly complete. 



27 

Leaf Miner No. 4 — The Autumnal Locust Leaf- 
miner (Lithocolletes robiniella). — About the first of Aug- 
ust a pure white blister, generally elongate-oval in out- 
line and restricted to one side of the midrib, appears, 
most often on the underside of the leaflets. It can be dis- 
tinguished from the yellow blotch-mine by the fact that 
it is not linear and tortuous at first. The egg is placed 
by the moth at the edge of the prospective blister, and the 
young grub produces a blotch-mine at once, only making 
it gradually larger with its own increase in size. By 
the third week in August some of these blisters contain 
quiescent pupae in little white cocoons, and by the last 
of August the adult moths come out. They are very sim- 
ilar to the moth of No. 3, but the silvery lines do not ex- 
tend entirely across the fore wings, and there is a dis- 
tinct black spot at the free ends of the wings. In addi- 
tion there are some golden lines alternating with the sil- 
ver. The "\\'ings are closely folded about the body when 
at rest. Over the head projects a dense tuft of bristly 
hairs, the central black, the others white. It measures 
about an eighth inch from the tip of the frontal bristles 
to the ends of the folded wings. 

The Locust Leaf-skeletoniser (Gelechia pseudacaci- 
ella). — Though not a leaf -miner, this insect is closely 
related with the three preceding species. It draws the 
leaflets together and lives between them, gnawing away 
the surfaces. It is very active in its movements and scur- 
ries back into its retreat when uncovered, and often when 
pursued further lets itself drop from the foliage by 
means of a silken thread which it emits from its lower 
lip. The fully grown worm is three-fourths of an inch 
long, pale green in general color, with brown head and 
six pale longitudinal stripes. The very young larvae are 
darker in hue. These skeletonizers are found among the 
leaves from June to October. Pupae are found in July, 
and adults emerge from them in August, placing eggs for 
a late brood. The adult moth has a wing expanse of two- 
thirds of an inch. It is dusky in general color, marked 
with black and ash-gray. 

The Locust Skipper (Eudamns titi/rus). — This is a 
much larger insect than the preceding miners and skele- 
tonizers and as an adult is very common about clover 



28 

blossoms and other flowers during the summer. It is a 
brown butterfly with a large silvery blotch on the under 
side of each hind wing. The young, wdiich works in 
locust leaves, is a thick-bodied, yellowish green worm, 
with a singular, large, reddish brown head marked with 
two large, round, yellow spots resembling eyes. It draws 
the leaflets together and lives within and feeds upon 
them. The brown pupa is formed in these shelters and 
is the condition in which the insect spends the winter. 

Puncturing Insects. 

A good many insects puncture the leaves or young 
twigs and suck the sap. They are common enough at 
times to weaken the trees greatly, but ordinarily the mis- 
chief of a season is done by the gnawing insects. The 
following puncturing insects have been frequentl}^ ob- 
served on locust trees in Kentucky : 

Lopidea robiniae. — A common insect at times. 

Tree-liopper (Thelia himaculata). — One of the com- 
monest tree-hoppers on the locust, from the twigs of 
which it sucks the sap. It is not often observed because 
of its remarkable resemblance to some of the thorns on 
the twigs. I have been impressed with this resemblance 
more than once since my attention has been given to 
locust insects. If there is anything in the idea of "pro- 
tective resemblance," this is certainly an instance of it. 
The photograph shows very well the nature of the re- 
semblance. 

Tree-hopper (Vanduzea arcuata). — This insect is 
another common locust tree-hopper. It is gregarious in 
habit, and numbers, young and adult, are often found 
together on the twigs, where they are attended by a large 
black ant, probably after the sap also. 

Tree-hopper ( Acutalis colva). — A small, shining, 
black species, frequent on the trees. 

Tivo-spotted Tree-hopper (Euchenopa oinofata). — 
Not as common on locust as the two preceding. 

Buffalo Tree-hopper (Ceresa hrevicornis). — Occa- 
sionally found on the trees, 

Ormenis priiinosa. — Frequent. 

Flat a conica. — Occasional. 




Fig. 20. Leaflets rolled by the locust midge 
(Cecidomyia robiniael, a very common injury 
in Kentucky. Reduced. 



29 

Nesara 'pennsijlvanica. — This is one of the stink 
bugs, a broad, flat, green species, sometimes found about 
the trees. 

Empoasca mali. — Frequent. 

Empoasca splendida. — Common. 

Typhlocyha que rci-hif asciat a . — OccasionalT 

Diedrocephala roccinea. — Not rare. 

AcantJiia multispinosa. — Frequent. Like the wheel 
bug, this smaller insect is predatory. It probably attacks 
some of the small, injurious locust insects, but has not 
been observed doing so on the trees. In confinement it 
catches and destroys large numbers of flies. 

Treatment for Gnawing and Puncturing Insects. 

While the number of species gnawing, mining and 
puncturing the leaves is large it is not to be supposed 
that they render the growing of locust trees unpromising 
as a business proposition. They can be controlled in 
most cases by spraying and by care in gathering up and 
destroying rubbish about the trees when they become 
numerous and are likely to hibernate in large numbers 
about the plantings. A spray of three or four pounds of 
arsenate of lead paste in a barrel of water should destroy 
most of the gnawing species. The puncturing sorts are 
more difficult to deal with, but sprays of lime-sulphur in- 
winter, and of coal-oil emulsion should suppress these 
also. In fact, after watching these insects for two sea- 
sons, I am of opinion that the locust borer presents a 
more serious problem than all of tlie others together. 

The Goldenrods. 

The name "goldenrod" is applied to these plants 
because of the frequent arrangement of the small heads 
of yellow flowers in close, often cylindrical, spike-like 
thyrses, or terminal panicles. They constitute a con- 
spicuous feature of our late summer native plant life. 

Along roadsides, on railroad right-of-ways, at the 
edges of fields, in thickets, along streams, the bright yel- 
low hues of the flowers always appeal to the eye of the 
artist and nature lover, present in us all in large or 
small measure, and add to the attractiveness of the coun- 



30 

try at a time when cultivated crops are likely to be in a 
sere and unpleasing state. We shall lose something of 
the pleasure of living when these sprightly autumn flow- 
ers have all been banished from our fields. That they 
appeal to most of us is shown by the frequency with 
wdiich they have been chosen as State Flowers. Even in 
Kentucky the goldenrod has had many votes as a flower 
representative of the Commonwealth. 

But the term ''goldenrod" has a very vague mean- 
ing when we consider the large number of species of 
plants properly so called. In the United States there are 
no less than 74 species, with numerous named varieties. 

Seventeen species of the genus Solidago occur in 
Kentucky and perhaps a few more. An additional 
species (Brachychaeta spliacelaia), sometimes in bot- 
anies called the false goldenrod, is regarded as a golden- 
rod, without question, by those not familiar with the 
obscure characters which have led botanists to place it 
in a separate genus ; so for all practical purposes we may 
say that there are eighteen known Kentucky goldenrods. 

They differ widely in character, with species, and 
to some extent with the situation and soil in which they 
grow. For while the different species show marked ten- 
dencies to thrive and become numerous in particular sit- 
uations, chance often plays a part in their distribution 
and influences their character. 

Thus such species as Solidago altissima are at their 
best on low^, moist, rich ground, where they are often five 
or six feet in height; on higher, drier ground they are 
not so tall, though still showing a tendency to rankness 
of growth. They are pretty generally plants of the open 
fields, and are not at all disposed to invade woodland. 
Solidago latifolia and S. ulmifolia are examples of slight, 
low-growing plants, being commonly only eighteen 
inches or thereabouts in height, and are found along- 
rocky wooded banks or bluff's. 

The species are in some cases so closely related that 
even botanists find difficulty in separating them. The 
difficulty is enhanced by the disposition of some of them 
to hybridize, and the amateur flower lover is to be ex- 
cused when he is unable to place to his satisfaction all 
the plants of the genus he finds. 




Fig. 21. Several panicles of the Tall Golden- 
rod (Solidago altissima) flowers; greatly re- 
duced. 




Fig. 22. A single panicle of the Tall Goldenrcd, showing; the characteristic 
curve and dronn of the liranchlets; natural size. 



oL 

The characters most depended on are the shape and 
size of the flower chisters, the shape of the leaves, and 
the presence or absence of down on stems, leaves and 
developing seeds (achenes). 

As examples of two extremes -S'. lot if alia and S. altis- 
sima may be selected. The former bears the flowers in 
small isolated clnsters along the stem in the axils of the 
upper leaves, sometimes with a continuous cylindrical 
assemblage several inches in length at the tip. There are 
no very long lateral flower-bearing branches. The leaves, 
too, are broad, oval, the width sometimes two-thirds to 
three-fourths the length, S. altisslma, on the oth^r hand, 
is a tall, stout-stemmed plant, with narrow, tapering- 
leaves, the flowers restricted largely to a large, wide- 
spreading terminal panicle, the lower branches of wliich 
may be six inches or more in length. 

Some of the native species are now listed by dealers 
in florists' stock, but are not as much grown at the pres- 
ent time as they deserve to be, merely for their oeauty. 
Some of them deserve attention, also, because of reputed 
medicinal value. The European Solidago virgaurea was 
at one time employed in medicine. Solidago odora of 
this country is also said to have some value of this sort. 
The word Solidago means to make whole, and has ref- 
erence to the use of infusions of the plant to cure wounds. 

A yellow dye has been obtained from some of the 
species. The name Dyer's Weed, applied to S. nemo- 
ralis, seems to have reference to this use of the plant. 

The following species occur in Kentucky: 

Wreath Goldenrod (Solidaqo cars'ia). In woods. 
High Bridge, Oct. 15, 1892. Natural Bridge, Oct. 21, 
1911. Earlington, Oct. 3, 1914. Central City, Oct. 5, 1 914. 

Broad-leaved Goldenrod (Solidago lafifolia). 
Shaded banks and bluffs in rich soil. Elk Lick Falls, 
Aug. 17, 1892. High Bridge, Oct. 15, 1892. Frankfort, 
Sept. 30, 1914. Clifton, Oct, 4, 1914. 

Curtis' Goldenrod (Solidago nirtisH). Kentucky 
(Gray's Manual). Said to occur in mountain woods. 

Pale Goldenrod (Solidago bicolor.) Kentuckj' 
(Gray's Manual), Dry soil. 

Puberulent Goldenrod (Solidat/o puhcnila). Sol- 
dier, Ky., Sept. 9, 1893. 



32 

Early Golclenrod (Solidago juncea). McHenrv, 
July 30, 1892. Leitclifield, Aug. 7, 1904. Dry soil. 

Anise-scented Goldenrod (Solidago odora). Nat- 
ural Bridge, Oct. 21, 1911. Dickey's Mills, July 14, 1896. 

Elin-leaved Goldenrod (Solidago ulmifolia). Elk 
Lick Falls, Aug. 17, 1892. Benson Creek, Frankfort, 
Sept. 30, 1914. Edges of woods. 

Rougli-leaved Solidago (Solidaqo rugosa). Natural 
Bridge, Aug. 29, 1915. 

Short's Goldenrod (Solidago shortii). Clay's 
Ferry, Aug. 22, 1892. Among rocks along streams. 

Dyer's Weed (Solidago nemoralis). Hopkinsville, 
Aug. 8, 1892. Eicliland, Aug. 19, 1904. Dry soil in the 
open. 

Canadian Goldenrod (Solidago canadensis). Lexing- 
ton, Aug. 29, 1892. Nortonville, Aug. 7, 1892. Tarascoii, 
Aug., 1910. Rich soil in tangles of herbage, etc. 

Rock Goldenrod (Solidago rupestris). Clifton 
Banks of Kentucky River, Oct. 4, 1914. 

Tall Goldenrod (Solidago aUissima). Lexington, 
Sept. 12, 17, and Oct. 8-12, 1914. Clifton, Oct. 4, 1914. 
Earlington, Oct., 1914. Aden Springs, Oct. 2, 1892. 
Common in rich soil in open situations. 

Late Goldnrod (Solidago serotina). Tyrone, Aug. 
25, 1892. 

Ohio Goldenrod (Solidago ohioensis). McHenry, 
July 30, 1892. Wet land. 

Flat-topped Goldenrod (Solidago graminifolia). 
Nortonville, Aug. 7, 1892. Waco, Aug. 20', 1902. Moist 
situations. 

False Goldenrod (Brachychaeta sphacelafa). Elk 
Lick Falls, Aug. 17, 1892. Clifton, Oct. 4, 1914. Wooded 
banks of streams. 

Summary and Suggestions. 

1. The locust borer is a black and yellow beetle 
when adult, occurring from the latter part of August 
until late October on the flowers of goldenrod, particu- 
larly on those of the common, rank-growing species 
known as Solidago altissima. ; " 

2. The injury is done to locust trees by the grubs 
or immature beetles which mine the trunks and branches, 




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being most active from May until mid- August, when they 
become quiescent pupae within the burrows. 

3. The food of the borer is the wood of the locust 
trees; that of the adult, the pollen of goldenrod. 

4. Since the adult insects seem dependent on pol- 
len and are abundant only where it may be secured it is 
suggested as a means of lessening the injuries, that all 
g" Idenrod in the vicinity of plantings be destroyed, or be 
s])i-ayed witli arsenate of lead in early Sexjtember so as 
to destroy the beetles. A spray consisting of three or 
lour ]K)niids of the prison in a barrel of water should be 
used. 

5. Spraying the trunks of trees with the same poi- 
son is suggested as a further precaution, and should be 
a.p|jlied about the first of September when the beetles 
begin to emerge from the trees. 

G. Old, badly infested locust trees in the vicinity of 
plantings serve as a breeding place for the borers and 
if of no value should be destroyed. 

7. Baits other than goldenrod have thus far not 
|)i(>ved very successful. A few beetles were cay^tured in 
fly tra})s hung in young trees near the Station Building, 
and ])aited with banana, but the number was not large. 
]\l()i-e of the beetles were attracted to Solidago of several 
species, near by. 

S. The gathering of the beetles from goldenrod by 
ehildi-en, as suggested years ago by Harris, is not, it 
seems to me, impracticable for all plantings and would no 
doubt reduce the injuries. 

9. The locust borer is not evenly distributed over 
the State. It is most numerous and injurious on open 
tracts of good soil where the Tall Goldenrod, Solidaf/o 
(iltissima, is most abundant. It becomes less common in 
those parts of the State where this plant and the closely 
i-elated Solirhifio canadensis are least common. It feeds 
upon other goldenrods when the above species are not 
present, but these two bloom at the time when the adult 
borers conu' from the trees and appear to be their main 
dependence for food. 

the mountain counties, accordingly, the injury to 
loc is is less severe than elsewhere, and this region af- 
I'oi' tliousands of acres of cheap land upon which the 



trees may at present be grown witli tJie assurance that 
the injury will be less severe than elsewhere in the State. 
By keeping goklenrod of all sorts suppressed in the 
vicinity of plantings that may be established there the 
chances seem to me good to keep the injury from becom- 
ing severe in the future. 



NOTE. — The writer is indebted to several members 
of the Staff of the Department for assistance of one sort 
or another in making this study. Assistant Professor 
Vaughn has made many of the photographs. Messrs. 
Jewett and Niswonger examined the commercial plant- 
ings of locust and from time to time have collected ma- 
terial for examination. A student, Mr. Leon Leonian, 
has aided by cutting out larvae and pupae, and on one 
occasion collected from the foliage of trees in this neigh- 
borhood the miscellaneous insects commonlv found there. 



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